scholarly journals Effect of Different Nucleating Agents on the Crystallization of Ziegler-Natta Isotactic Polypropylene

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Felipe Avalos-Belmontes ◽  
Luis Francisco Ramos-deValle ◽  
Adriana Berenice Espinoza-Martínez ◽  
Juan Guillermo Martínez-Colunga ◽  
Eduardo Ramírez-Vargas ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanofibers ◽  
Isotactic Polypropylene ◽  
Crystallization Temperature ◽  
Carbon Nanoparticles ◽  
Crystallization Process ◽  
Life Time ◽  
Nucleating Agent ◽  
Crystalline Form ◽  
Nucleating Agents

Ziegler-Natta isotactic polypropylene (iPP) was melt mixed with four different nucleating agents (carbon nanotubes (CNT), carbon nanofibers (CNF), lithium benzoate (LiBe), and a sorbitol derivative (Millad)) in order to study their effect on the crystallization of iPP. It was found that the four different nucleating agents promote the alpha crystalline form. At 0.01 wt%, the carbon nanoparticles produced the higher crystallization temperature “Tc” (~119°C), whereas, at 0.10 wt%, LiBe and Millad produced a markedly higherTc(~125°C).Tcof pure iPP was 111°C. With 0.1 wt% nucleating agent, at 120°C, the crystallization half-life time of PP, when using LiBe or Millad, was 15 times faster than for pure PP, whereas, when using carbon nanoparticles, it was 20–25 times faster. At 135°C, with 0.01 wt% nucleating agent, the isothermal crystallization process of iPP was completed after 25 min, as well as with Millad. With LiBe, it was completed after just 15 min and, with any of the carbon nanoparticles, it was practically over after only a couple of minutes.

Preparation, Characterization of Substituted Aromatic Heterocyclic Phosphate Salts and the Application in Isotactic Polypropylene

2013 ◽  
Vol 652-654 ◽  
pp. 463-469
Author(s):  
Li Juan Long ◽  
Wen Tao He ◽  
Min Min Zhang ◽  
Kai Zhang ◽  
Min He ◽  
...  
Keyword(s):  
Optical Properties ◽  
Isotactic Polypropylene ◽  
Crystallization Temperature ◽  
Nucleating Agent ◽  
Nucleating Agents ◽  
Absorption Bands ◽  
Nucleation Effect ◽  
Stretching Vibration ◽  
Phosphate Salts ◽  
Aromatic Heterocyclic

Substituted aromatic heterocyclic phosphate salts were synthesized by a new method and characterized by fourier transform infrared spectroscopy(FT-IR) and thermogravimetry (TG) method. The characteristic absorption bands ascribed to the stretching vibration of P=O group and P-O group verify the successful synthesis of substituted aromatic heterocyclic phosphate salts. When compared with sodium salt, the thermal stability of other salts declines. Their nucleation effects on isotactic polypropylene(iPP) were investigated with differential scanning calorimeter(DSC) and influences on mechanical, optical properties of iPP were also studied. The DSC result shows that with 0.15wt% nucleating agents incorporated into iPP, monovalent salts have a good performance, bivalent salts have less nucleation effect on the crystallization temperature. But the mass fraction of crystallinity of iPP with manganese salt could be increased by 5.2% even it has a weak ability relatively on crystallization temperature. And the mechanical and optical properties of iPP with manganese salt almost reach to iPP containing lithium salt. The results demonstrate that bivalent manganses salt is a kind of new effective nucleating agent when designing compound nucleating agents.

scholarly journals Carbon Nanofibers from Carbon Nanotubes by 1.2 keVAr+Sputtering at Room Temperature

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Shuang-Xi Xue ◽  
Qin-Tao Li ◽  
Xian-Rui Zhao ◽  
Qin-Yi Shi ◽  
Zhi-Gang Li ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Carbon Nanofibers ◽  
Carbon Nanoparticles ◽  
Room Temperature ◽  
Ion Irradiation ◽  
Transmission Electron ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes ◽  
Carbon Nanowires

Multi-walled carbon nanotubes (MWCNTs) were irradiated by 1.2 keV Ar ion beams for 15–60 min at room temperature with current density of 60 µA/cm2. The morphology and microstructure are investigated by scanning electron microscopy, transmission electron microscopy and Raman spectroscopy. The results show that carbon nanofibers are achieved after 60 min ion irradiation and the formation of carbon nanofibers proceeds through four periods, carbon nanotubes—amorphous carbon nanowires—carbon nanoparticles along the tube axis—conical protrusions on the nanoparticles surface—carbon nanofibers from the conical protrusions.

Effect of Different Nucleating Agents on the Microstructure and Properties of LMAS Glass-Ceramics

2012 ◽  
Vol 535-537 ◽  
pp. 819-823
Author(s):  
Wei Hui Jiang ◽  
Yuan Fa Wu ◽  
Jian Min Liu ◽  
Qing Xia Zhu ◽  
Xun Yan Tan ◽  
...  
Keyword(s):  
Solid Solution ◽  
Flexural Strength ◽  
Crystallization Temperature ◽  
Coefficient Of Thermal Expansion ◽  
Glass Ceramics ◽  
Nucleating Agent ◽  
Crystal Phase ◽  
Nucleating Agents ◽  
Microstructure And Properties ◽  
Sintering Method

Li2O-MgO-Al2O3-SiO2(LMAS) system glass-ceramics had been prepared by sintering method. The effect of different nucleating agents on the phase composition, microstructure and properties of LMAS system glass-ceramics were investigated by DTA, XRD and SEM. The results indicate that the introduction of nucleating agents could contribute to decreasing the crystallization temperature of the glass-ceramics, the effect of the nucleating agent TiO2 is most obvious, and the crystallization temperature is the lowest(798.9°C). Main crystal phase of the glass-ceramics without the nucleating agents is β-quartz solid solution, while main crystal phase of the glass-ceramics with different nucleating agents changes into β-spodumene solid solution. The glass-ceramics with composite nucleating agents (TiO2+ZrO2+P2O5) are the lowest coefficient of thermal expansion (0.86×10-6/°C)and the highest flexural strength (95MPa). Composite nucleating agents have the best effect of crystallization, and contribute to the formation of a large number of short columnar crystals, which is the main reason for obtaining glass-ceramics with low expansion coefficient and high flexural strength.

Crystallization of Polypropylene Induced by the Aqueous Dispersion of Isotactic Polypropylene Wax

2014 ◽  
Vol 692 ◽  
pp. 255-260
Author(s):  
Xin Yi Zhao ◽  
Ke Zhao ◽  
Pei Qin Sun
Keyword(s):  
Isotactic Polypropylene ◽  
Polarized Light ◽  
Aqueous Dispersion ◽  
Nucleating Agent ◽  
Nucleating Agents ◽  
Melting Points ◽  
Aqueous Dispersions ◽  
Nucleation Agents ◽  
The Difference ◽  
Crystal Content

The Polarized light microscope and DSC are used to study the influence of the nucleation agents’ type (The aqueous dispersion of isotactic polypropylene wax and the commercial nucleating agent TMB-5), nucleating agents’ content on the β-crystal content, melting points of α-crystal and β-crystal are studied in the paper. The difference of their capacities of inducing the crystallization of polypropylene are compared and analyzed. The foundation of the treatment of the aqueous dispersions of isotactic polypropylene wax on the reinforcements to induce crystallization on the surfaces of the reinforcements is laid.

scholarly journals Investigation on the Effects of MXene and β-Nucleating Agent on the Crystallization Behavior of Isotactic Polypropylene

Polymers ◽  
2021 ◽  
Vol 13 (17) ◽  
pp. 2931
Author(s):  
Wanxin Peng ◽  
Jian Kang ◽  
Xiuduo Song ◽  
Yue Zhang ◽  
Bo Hu ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Rare Earth ◽  
Isotactic Polypropylene ◽  
Crystallization Behavior ◽  
Nucleating Agent ◽  
Melting Behavior ◽  
Nucleating Agents ◽  
Structure And Morphology ◽  
Β Phase ◽  
Α Phase

The effects of MXene on the crystallization behavior of β-nucleated isotactic polypropylene (iPP) were comparatively studied. The commonly used MXene Ti3C2Tx was prepared by selective etching and its structure and morphology were studied in detail. Then MXene and a rare earth β-nucleating agent (NA) WBG-II were nucleated with iPP to prepare samples with different polymorphic compositions. The crystallization, melting behavior, and morphologies of neat iPP, iPP/MXene, iPP/WBG-II, and iPP/MXene/WBG-II were comparatively studied. The crystallization behavior analysis reveals that a competitive relationship exists between MXene and WBG-II when they were compounded as α and β nucleating agents. In the system, the β-nucleation efficiency (NE) of WBG-II is higher than α-NE of MXene. The β-phase has relatively low thermal stability and would transform to α-phase when cooled below a critical temperature.

Enhanced Structural Behavior of Systems Polypropylene-Carbon Nanotubes in Acidic Medium

2014 ◽  
Vol 1613 ◽  
pp. 115-120
Author(s):  
Felipe Avalos-Belmontes ◽  
Miguel Flores-Godina ◽  
Rosa Narro-Cespedes ◽  
Adali Castañeda-Facio ◽  
Martha Castañeda-Flores ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Crystallization Temperature ◽  
Morphological Changes ◽  
Oxidative Degradation ◽  
Nucleating Agent ◽  
Decomposition Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Negative Effect ◽  
Alpha Type

ABSTRACTThe effect of carbon nanotubes (CNTs) on the thermal and chemical stability of polypropylene (PP) when subjected to oxidation in a fuming nitric was evaluated. The effect of CNTs on the crystalline morphology and melting and crystallization temperature of PP was studied. The results shown a thermal stability increased markedly; the decomposition temperature, increased from 293°C for pure PP to 320°C for PP with CNTs. The crystallization temperature increased perceptibly in presence of CNTs. The oxidative degradation with nitric acid produced a reduction in molecular weight; however, this negative effect was less pronounced in the PP compositions with carbon nanoparticles. The morphological changes evaluated with X-ray diffraction showed that the alpha type crystallinity remains, irrespective of the nucleating agent, and the intensity ratios between reflections peaks was taken as an indication of an increasing nucleating efficiency.

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